The present invention relates to a tungsten-halogen light bulb and a reflector lamp using the tungsten-halogen light bulb.
Tungsten-halogen light bulbs generally are used for lighting at shops and residences.
Conventionally, such tungsten-halogen light bulbs can be classified into a low-voltage type and a high-voltage type. Low-voltage type refers chiefly to a light bulb rated at 12V, while high-voltage type refers to, for example, a light bulb rated at 100V or 110V in Japan, 120V in the United States, and 230V or 240V in Europe. The tungsten-halogen light bulbs can be classified further into a single-based type bulb having a seal portion at only one end, and a double-based type bulb having seal portions at the both ends.
Among the above-identified conventional tungsten-halogen light bulbs, a single-based tungsten-halogen light bulb has an arc tube, and one end of the arc tube is sealed. Inside the arc tube, a filament and two inner lead wires holding this filament are provided. Moreover in the arc tube, a basic gas mainly comprising gaseous xenon, gaseous krypton, gaseous argon or the like is filled.
A base is fixed with an adhesive at the seal portion.
The inner lead wires are connected to outer lead wires through a metal foil sealed at the seal portion. These outer lead wires are connected to the base.
For such a single-based tungsten-halogen light bulb, especially when it is a tungsten-halogen light bulb of a high-voltage type, the pressure for filling the basic gas at a room temperature (25xc2x0 C.) is decreased to, for example, 0.2 MPa or less in order to reduce damage to the arc tube.
In such a high-voltage type tungsten-halogen light bulb, however, the filament will be broken at the end of the lifetime. As a result, arc discharge will be induced between the cross sections of the broken filament. This arc discharge shifts in the inner lead wires to the vicinity of the seal portion, and causes thermal shock, and thus, cracks will occur at the seal portion. Specifically, this thermal shock is caused by the arc discharge and also by heat at the overheated inner lead wires.
Furthermore, in the conventional high-voltage type tungsten-halogen light bulb, tungsten in the filament evaporates, and this triggers breakdown of the filament to shorten the lifetime.
To solve the above-mentioned problems, the present invention provides a tungsten-halogen light bulb and a reflector lamp using the tungsten-halogen light bulb. The tungsten-halogen light bulb can prevent crack occurrence at the seal portion of the arc tube and it has a long life.
To achieve the above-mentioned purpose, a tungsten-halogen light bulb of the present invention has an arc tube having a seal portion at one end. A filament is provided in the arc tube, and a basic gas mainly comprising at least either gaseous xenon or gaseous krypton is filled in the arc tube.
When V (Volt) denotes a rated voltage of the tungsten-halogen light bulb, P(MPa) denotes a filling pressure of the basic gas at a room temperature, and Xe vol. % and Kr vol. % respectively denote composition ratios of the gaseous xenon and the gaseous krypton, the following formulas (1) and (2) are satisfied at the same time.
Vxe2x89xa7100 (Volt)xe2x80x83xe2x80x83(1)
Pxe2x89xa70.7+{0.1xc3x97(Kr%/(Kr%+Xe%))}xe2x80x83xe2x80x83(2)
In these formulas, Kr %+Xe %=100(%), 0xe2x89xa6Kr %xe2x89xa6100, and 0xe2x89xa6Xe %xe2x89xa6100.
A reflector lamp of the present invention comprises a tungsten-halogen light bulb and a reflector provided with a front glass. The tungsten-halogen light bulb has an arc tube with a seal portion at one end. A filament is provided in the interior of the arc tube and a basic gas mainly comprising at least either gaseous xenon or gaseous krypton is filled in the arc tube.
When V (Volt) denotes a rated voltage of the tungsten-halogen light bulb, P(MPa) denotes a filling pressure of the basic gas at a room temperature, and Xe vol. % and Kr vol. % respectively denote composition ratios of the gaseous xenon and the gaseous krypton, the following formulas (1) and (2) are satisfied at the same time.
Vxe2x89xa7100 (Volt)xe2x80x83xe2x80x83(1)
Pxe2x89xa70.7+{0.1xc3x97(Kr%/(Kr%+Xe%))}xe2x80x83xe2x80x83(2)
In these formulas, Kr %+Xe %=100(%), 0xe2x89xa6Kr %xe2x89xa6100, and 0xe2x89xa6Xe %xe2x89xa6100.
Accordingly, the present invention provides a long-life tungsten-halogen light bulb that can prevent crack occurrence at the seal portion, and the present invention provides also a reflector lamp using the tungsten-halogen light bulb.